Redmond has won a motion to end the class-action status of the Windows Vista Capable lawsuit, although it lost a motion that could have ended the suit without a trial.

The motion to end the class-action status of the lawsuit means the plaintiffs will have to sue Microsoft individually, instead of as a group that could have drawn in potentially thousands of other consumers who felt wronged by the issue.

"We're pleased that the court granted our motion to decertify the class, leaving only the claims of six individuals," said David Bowermaster, a Microsoft spokesperson, in an email. "We look forward to presenting our case to the jury, should the plaintiffs elect to pursue their individual claims."

The case centres on claims that Microsoft misled computer buyers with the Vista Capable advertising campaign nearly a year prior to the release of the operating system. Plaintiffs argue they overpaid for computers due to the Vista Capable campaign and that the PCs they bought could only run the lowest-priced version of Vista, Home Basic, which they say is not a true Vista OS because it lacks key features of the other Vista versions.

Microsoft lost a request for a summary judgement, a ruling based on facts presented ahead of the trial. The company has argued that the plaintiffs have not demonstrated that Vista Home Basic was not the 'real Vista' nor that consumers overpaid for PCs because of the Vista Capable ad campaign.

The downside for Microsoft is that the case will now go to trial should the plaintiffs opt to continue. The company has already seen a stream of embarrassing emails made public through the lawsuit.

In the ruling, US District Court Judge Marsha Pechman said that while class action status is no longer appropriate for the case, it makes "no comment" on the claims people paid higher prices for PCs as a result of the Vista Capable Campaign.

"Defendant is mistaken to equate Plaintiffs' failure to provide class-wide proof of causation with a failure to present an issue for trial," she wrote in a 17-page ruling.

Elizabeth Montalbano also contributed to this report.